Electrical apparatus



Dec. 24, 1929. D. c. BE'rTlsoN v 1,741,007

I ELECTRICAL APPARATUS Filed July 22. 1,927

Patented Dec. 24, 1929 PATENT OFFICE DAVID C. BETTISON, OF OMAHA, NEBRASKA ELECTRICAL APPARATUS Application filed July 22,

My invention relates to electrical apparatus, and particularly toapparatus for at times supplying a load with both alternating and direct current. My invention is particularly adapted for, though in no way limited to, use in railway trailic controlling systems in which both alternating and direct currents are supplied to the trackway.

I will describe several forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing one form of electrical apparatus embodying my invention.

Figs. 2, 8 and l are views showing modified forms of the apparatus shown in Fig. l and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. l, the reference characters l and l, designate the track rails Vof a stretch of railway track along which trailic moves in the direction indicatedby the arrow.

These track rails are divided, by means of inf Sula-ted joints 2, into a plurality of successive track sections A--B, B-G, etc. Each track section is provided with a track relay designated by the reference character R with `a suitable distinguishing exponent and connected across the rails of the corresponding section. Each track relay R is intended to4 operate upon direct current, and is not responsive to alternating current yflowing therethrough. For supplying direct current to the rails of the track section for the control of the track relays R, a track battery is connected across the rails adj acent the right-hand end of each section, each such battery being designated by the reference character D with an expo- 40 nent corresponding to the location.

Means are also provided for at times supplying each track section with alternating current which may be used to control train carried governing means not sho-wn in the drawing. For present purposes it will be suiiicient to state that when the section of track occupied by the train is being supplied with alternating current, a proceed indication is received on the train and when the supply of such alternating current to the track- 1927. Serial N`0. 207,610.

way is for any reason interrupted, al stop indication is received on board the train.

In the present embodiment of my invention, the source of alternating current for each track section is a track transformer designated by the reference character T with a suitable distinguishing exponent, and having a primary 4l supplied with energy from secondary l0 of an associated line transformer K over a front contact 9 of the track relay R for the section next in advance. The primary ll of each line transformer K is constantly supplied with alternating current over line wires 30 and 80a from a suitable source of energy such as an alternator G. The primary 3 of each track transformer T is connected across the rails of the corresponding section in series with the associated battery D and the usual reactor 5 and resistor 6.k

With the arrangement thus far described it will be seen that each track battery Diconstantly supplies direct current to the rails of the corresponding section so that each of the track relays R is energized at all times except when the section is occupied by a train. Furthermore, alternating current is supplied to the rails of each section in series with the corresponding track battery D at all times except when the track relay for the section next in advance is cle-energized.

As shown in the drawing, a train indicated diagrammatically at V occupies the section to the right of point C, so that relay RC is de-energized, with the result that the primary circuit of transformer TC is open at front contact 9 of relay RC, so that no alternating current is supplied to the rails of section B C. The current supplied to section B-G from battery DC energizes relay RB, so that both alternating and direct currents are supplied to the rails of section A-B.

In many instances the 'track batteries D shown in the drawing are primary batteries. Since these batteries are constantly connected with the track rails, the drain upon the batteries is continuous, and considerable expense and inconvenience are entailed in the frequent replacements thus made necessary.

I therefore propose to reduce the amount of energyy which must be supplied by `each track battery D by connecting an asymmetric unit 7 in series With a small resistance 8 across each track battery D and the secondary 3 of the correspon-ding track transformer T. Referring for example to the apparatus located at point B, during one half of each cycle of current from transformer TB this current tends to flow through battery DB in the same direction as the current supplied by this battery, and during this half cycle the asymmetric unit 7 offers a comparatively high resist-ance to the flow of current from the transformer through the unit. During the other half of each cycle, however, a considerable current ioivs from the transformer through unit 7 and battery DB, it being noticed that the direction of the current through the battery DB under these conditions is contrary to the direction of the current supplied by the battery. During this half oycle'there is applied across the terminals of battery DB, a uni-directional electro motive force, which may be varied by variation of the resistance 8 to be of such value that the energy Which fioyvs into the battery during this half cycle is substantially equal to the energy Which flows out of the battery during the succeeding half cycle, and hence the net effect is that during a complete cycle substantially no energy is permanently taken from the battery. Under these conditions, however, the current in the rails of section A-B has a uni-directional component due to the uni-directional electromotive force er@ isting across the unit 7 and resistance 8.

As a result of this arrangement, the drain upon the track battery DB is materially reduced, because, during at least a portion of each cycle of the alternating current supplied by the transformer T, the iow of eurrent from the battery DPl is opposed, Without interference With the direct current component of the energy supplied to the trackyvay, The track relay R therefore operates in exactly the same manner as it would Without the asymmetric unit 7 connected in the circuit; but the total amount of energy required to be supplied by the battery D is materially reduced.

Of course, when the contact 9 of relay RB is open, no alternating current is supplied to the section A-B by transformer TB, and under these conditions, the entire amount of direct current supplied to the rails of section A-B must be furnishe-d by the battery DB. But even in systems Where the trackway is used by a large number of trains, the circuit for any given transformer T is open for only a comparatively insignificant portion of the time and I have discovered that a track battery provided `with an asymmetric unit connected in the manner shown in the drawing Will furnish the current required for the proper operation of the track relay with only a very small fraction of the drain the battery, I have observed that some of the active material utilized during the supply of energy by the battery is replaced on the electrodes by the brief surges of energy Which flow through the battery in the Charging direction with the apparatus embodying my invention.

Referring now to Fig. 2, With the arrangement here shown, the secondary 3 of transformer T is provided with the mid-tap a. The right-hand portion of this transformer secondary supplies the alternating current to the track rails for operating the train carried governing means, and the asymmetric unit 7 and the resistance 8 are connected across the entire secondary 3 and the battery D. The advantage of this arrangement is that a larger uni-directional electromotive force is available across the terminals of the battery D to oppose the normal flow of current supplied by this battery during the half cycles in which the current supplied by transformer T tends to oppose the current normally supplied by the battery D. The operation of the apparatus illustrated in this view will be readily understood Without further explanation.

In the modification illustrated in Fig. 3, a first secondary 3n of the transformer T Supplies alternating current to the track rails in series with the battery D. A second secondary 3b of the transformer T has its midpoint connected with one terminal of the bat tery D, and has its two terminals connected through asymmetric units 12 and 13, respectively, With the opposite terminal of the battery D. IVhen contact 9 of relay R is closed so that transformer T is energized, a unidirectional electromotive force is constantly applied across the terminals of the battery D in such direction as to oppose the flow of current .from this battery into the circuitnormally supplied with energy by the battery. lith this arrangement, as long as transformer T is energized, there Will be substantially no drain upon the battery D, although the current in the trackway has a uni-directional component as a result of the uni-directional electromotive force applied across the terminals of the battery D by the energy supplied by secondary 3.

In the modification shown in Fig. 4l, the asymmetric unit 7 is connected directly across the battery D and the resistance 6. During the Ahalf cycles in which the current from transformer T tends to flow in the direction opposite to that of the direct current supplied by battery D, substantially no current flows through unit 7. During half cycles of the opposite polarity, however, while current from transformer T flows through battery D, it also flows through unit 7, so that the total current in the transformer secondary 3 is greater during the half cycles that current flows through unit 7. It follows that the current actually supplied to the track rails is unbalanced, that is, this current has a direct current component which is effective to operate the relay R connected across the track rails. During the half cycles that the current does flow through the unit 7 in appreciable quantities, the potential drop across this unit is opposed to the current through battery D and the current furnished by t e battery is therefore reduced. As a result, a substantial saving is effected in the current supplied by battery D, and hence in the drain upon the batteryand its life is correspondingly increased. i

Although I have herein shown and described only a few forms of electrical apparatus embodying my invention, it is understood that Various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. In combination with a load, a battery normally supplying direct current to the load, a source of energy supplying alternating current to the load in series with the battery, and an asymmetric unit connected in circuit with the battery and effective during alternate half cycles of said alternating current to oppose the flow of current from the battery without substantially varying the direct current component of the current flowing through the load.

2. In combination with a load, a source of alternating current, a battery connected in series with the load and the source, and an asymmetric unit connected across said battery and said source.

3. In combination with a section of railway track, a source of alternating current connected across the rails of the section, a battery connected between the source and one rail, and an asymmetric unit connected in parallel with said battery and source.

4. In combination witha section of railwa track a rimarv batter connected across 5. In combination, a section of railway track, a transformer having its secondary connected across the rails of the section, means for at times supplying alternating current to the primary of said transformer, a primary battery connected in series with said secondary and a rail of the section, and means including an asymmetric unit and receiving energy from said primary for causing a current to flow at times through the battery in a direction contrary to the direction of the current supplied by the battery.

6. In combination with a load, a battery connected with the load, a source 0f alternating current for supplying alternating current to the load in series with the battery, and an asymmetric unit connected across said source and battery and disposed in such manner as t0 offer its higher resistance to current tending to flow from the battery through such unit and the source.

7. In combination with a section of railway track, a transformer having its primary supplied with alternating current, a primary battery having one terminal connected with one point on said secondary, means for connecting the free terminal of the battery with one rail of the section, means for connecting a second point on the secondary with t-he other rail of the section, and means including an asymmetric unit for connecting a third point on the secondary with said free terminal of the battery, said unit being connected in such manner as to oppose the flow of current supplied by the battery through the unit and said secondary.

In testimony whereof I affix my signature.

DAVID C. BETTISON. 

